The related applications describe and claim a power supply controller, and various features thereof, which can be used for controlling a plurality of isolating power supplies, such as switch mode power supplies or DC power converters, for providing controlled electrical power to loads. For example, the power supplies may provide different supply voltages to various electrical circuits on a circuit card on which the power supply controller is also provided.
In such a power supply controller, separate IC (integrated circuit) control units can be provided on the primary and secondary sides of a transformer that serves to maintain an electrical isolation barrier between input and output sides of the isolating power supplies. The transformer conveniently provides for signal coupling in both directions between the primary and secondary control units, and also for power transfer from its primary to its secondary side to supply operating power to the secondary control unit and any related circuits (for example, a non-volatile memory) of the power supply controller on the secondary side of the transformer.
In order to provide sufficient power transfer to the secondary side, the control unit on the primary side must be capable of providing substantial current drive to the primary of the transformer. To provide such a high current drive, while also complying with other requirements such as for signal levels, IC characteristics and limitations, and bidirectional signal transmission, a plurality of drivers may be used in parallel on the primary side of the transformer. For example, the control unit on the primary side may include of the order of ten such drivers to provide a drive current up to the order of 100 mA.
The present inventor has recognized that such use of a plurality of drivers in parallel can lead to a number of disadvantages, and that these disadvantages can be avoided or reduced by techniques of the present invention.
Conversely, similar disadvantages that may apply to other arrangements for transferring power via a transformer using only one driver, or using two or more drivers, on the primary side of the transformer can be avoided or reduced by using a plurality of drivers using techniques of the present invention. Accordingly, although the invention is described in detail in the context of a power supply controller, it can be appreciated that the invention is not limited to this particular application.